Method of making piston rings



Feb. 28, 1928.

H. W. HAMILTON METHOD OF MAKING PISTON RINGS Filed Jan, 12, 1927 Patented Feb. 28,1928.

HELEN W. MILTON, OI BROOKLYN, NEW YORK.

unrnon or name ms ron nmes.

Application filed'lanuary 12, 1927. Serial No. 160,568.-

This invention is a piston ring of the character which is both axially and radially expansible, whereby axial fitting of the ring to a piston groove or vice versa is obviated.

The object of the invention is to provide a ring of this character which ma be simply and economically manufactured and to further provide an economical manner for theproductio'n of such ring.

. manner of carrying out the present inven.

Features of the invention, other than those specified, will be apparent from the hereinafter detailed description and claims,

when read in conjunction with the accompanying drawings. I

The accompanying drawings ,show the tion in an illustrative way and also illustrate the preferred form of 'ring resulting from these operations. The invention is to be understood, however, exact steps or structure 1ngs.

Figure 1 shows a blankfrom which the ring of this invention is constructed.

Figure 2 is a side elevation, of the blank showing it as it appears after the upper edge of the ring has been faced and the ring'circumferentially slotted.

Figure 3 shows the blank of Figure 1 in cooperative relation to the magnetic chuck of a rinding machine and as the parts appear efore the chuck is energized.

shown" in the draw- Fi u're 4 is a YIBW slmilar to Fi ure 3, but s 10W1I1g the rlng as it appears 9. er the chuck is-energized.

Figure 5 shows the wheel moved to bring the ring into position tobe acted upon by the grinding wheel of the grinding machine.

Figure 6 shows the ring as it appears after its lower edge has been ground to the de sired extent; and,

Figure 7 shows the finished rin v In the accompanying drawings, have not attempted to show the parts to scale, but have greatly exaggerated different parts o the ring in order to more clearly set forth the method of this invention. v

In manufacturing the ring of the present invention, Imay use as a blank an ordinary plain ,unslit ring of slightly oversize axial dimension and split or jointed at 1 as usual.

This joint or split may he stepped as shown, or otherwise, as the, type of oint employed is not material to the resent invention.

The blank havin Eeen produced in the usual manner ofma ing a p ain' ring, I proas not limited to the ceed as follows. I first slit the blank by means of a circular saw or with any other suitable cutting tool to produce a succession of circumferential slots 3, all of which slots are of uniform width throughout and extend through the thickness of the ring blank. Preferably series of slots is employed and all the slots of this series are positloned in the same cross axial plane. These slots are, moreover, spaced apart circumferentially so as to provide interspaced, uncut circum erential portions 4 between the contiguous ends 'of 'adi acent slots.

After the slitting operation is completed, the ring blank is laid upon the surface of the magnetic chuck 6 of the grindin machine having a relatively movable grin ing wheel .5, as shown in Figure 3. In this fi ure, as

well as in Figs. 4, 5 and 6, the chuck is shown as positioned laterally of the wheel, and the parts may operate in this relation if desire altho, in practice, I prefer to have the surface of the chuck horizontal,

' with the wheel operating from above.

In Fig. 3, the blank is shown as laid on the face of the magnetic chuck with one edge 2 of the ring against the face of the chuck.

This ed e 2 is a finished edge and will con-.

stitute t e upper edge of the ring when in place in a ring groove of a piston. As shown in Fig. 3, the chuck has not been energized and, accordingly, the upper edge 2 and the edge 7, which will be the lower edge of the ring, ie in parallel .cross axial planes, the lane of the edge 7 being indicated by the inc 8.

After the blank has been placed against the face of the chuck 6, the chuck is energized with the result shown that is to say, those portions between the slots 3 and the lower edge 7 in Figure 4;

-- are drawn toward the magnet, as the magnetic forces act upon the blank, to grip it I and hold its finished edge 2 firmly against f the face of the chuck.

. While the chuck is energized as described, and the blank supported thereon, as shown in Figure 4, the grinding wheel 5 is moved into engagement with the ring blank, in order that the lower ed In other words, inasmuch as they are not 9 of the,blank p e of the blank may be round. The grin ing operation prothat while 1 center towards its ends.

vided which has an upper edge in the form' backed up, but are merelyheld against the wheel by their own resiliency, the grindlng of these portions 9 will not be as pronounced as will the grinding of the portions 4, whlch are, solid and are backed up directly by the chuck. As hereinbefore stated, moreover, the magnetic pull of the chuck Wlll serve to draw these portions 9 away from the wheel and thus minimize the grindin of these parts of the ring blank. It there ore follows that although at the commencing of the grinding operation, the parts appear as shown in Figure 5, these parts at the conclusion of the grinding operation will appear as shown in Figure 6. I

From this latter figure, 1t Wlll be noted that the lower edge 7 of the ring has been ground substantially flat, whereas the slots 3 will be of less width at their centers than at their extremities by virtue of the magnetic pull to which I have referred. If a chuck other than the magnetic chuck is employed to hold the ring in position, this particular formation of the slots will not be present as the slots will, in the absence of a magnetic pull, maintain their constant width at all times except when the grinding wheel 1s passing over the contiguous portions 9, when these portions will be flexed to constr1ct the central portions of the slots in succession. In either event, when the wheel is backed away from the chuck and the ring removed, it will immediately assume its finished form, shown in Figure 7, wherein all of the slots 3 will be of uniform width throughout, while each of the portions 9 will taper from its A ring is thus proof a plane surface, and a lower edge in the form of a succession of undulations the high points of which are centrally located with respect to the slots 3.

During the grinding operation, the intermediate portions 4 are ground to an axial dimension sufliciently less than the height of the'ring groove of the piston to allow of ample clearance under.all conditions,- but this grinding leaves the central parts of the portions 9 substantially unaffected, so that at these points, the ring is of mension than the ring groove. This neces sita-tes axial compression of the ring when inserting it into a ring groove, but it necessarily follows that the maximum axial dimension of the ring must not be in excess of the height of the ring groove plus the width of the slots 3, other ise the ring could not be introduced into the groove. 7

The grinding of the'ring in the manner described causes the to taper from their centers toward the portions 4. This causes the portion 9 to function in practice after the mannerof leaf springs to hold the upper edge 2 of the ring tightly against the top of the ring groove of greater axial di-- portions 9 ofthe ringthe piston, so that it conforms throughout its entire extent with the upper face of said groove.

The process of the present invention may 'be economically operated to produce a ring of high efficiency. During the manufacture of the ring, bending'strains and stresses, as would tend to warp the ring or throw it out of true, so that at the completion of the operation, the upper edge 2 of the ring, as well as its circumferential surface, which coacts with the cylinder wall are as true as they were in the original blank, after the latter was surfaced at the edge 2. I am thus enabled to economically produce a thoroughly .eflicient rugged construction with one series of slots havlng a greater quantity of material in its cross section than would be possible if a plurality of series of slots were employed as is generally the case in prior rings. is thus produced and one which will with stand wear and tear better than those rings which have a plurality of. series of slots. I have specifically referred to the use of a magnetic chuck in carrying out the grinding step of the process of this invention. I prefer to use a magnetic chuck in this connection, for thereason that it will hold the ring tightly in position without permanently warping or twisting the ring out ofshape during the grinding, of the lower edge of the ring.

I wish it understood, however, that an other chuck than the magnetic chuck which will hold the ring to the grinding wheel without ermanently warping it or twisting it and w iile maintaining its upper surface 2 in plane form comes within the purview of the process of this invention.

The herein described process is that prefera' ly employed in constructing the ring of this invention, but I do not limit the article to this particular method of manufacture.

The ring of this invention will adapt itself to ring grooves even though such grooves are badly worn, i. e., even if they are worn much wider than their original standard width. According to present practice, oversized rings are generally fitted into these grooves, but the ring of the present invention will properly conform to a worn groove in the piston and function properly therein.

, I wish to particularly point out that the method of making a ring as described does not contemplate any permanent distortion of the blank in the formation of the ring. Experience has shown that when attempts are made to draw, swedge, or otherwise bring about a pronounced distortion of a portlon of the ring, that all portions of the the parts are not subjected to A stronger ring ring will be distorted and that for this reason, the distortion of only a portion of the ring is not practical. There is no permanent dlstortion of the parts in the manuarcuate facturing of the ring of this invention. There is a slight springing within'the elastic limits of the parts during the grinding operation, but this is in no sense a distortion of the parts beyond'their elastic limits as has frequently been attempted in rings of the prior art.

The ring of the present invention is maintained perfectly true during the grinding operation by the fact that the upper face of the ring bears againstthe chuck and is held tightly against the plane surface thereof, so that there are no twisting strains or other detrimental steps in the manufacture as would bring about inaccuracies in the. finished ring.

The process may be simply performed by standard ring grinding apparatus, and may be accomplishedwith expedition and economy. The finished ring is thoroughly efficient in the performance of its intended functions. r i

Having thus fully described the invention, what I claim as new and desire to secure by Letters Patent is:

1. The herein described method of making piston rings, which consists in slitting a ring blank 'circumferentia'lly' into a succession' of arcuate slots with interspaced unslit portions, and thereafter grinding one edge of the ring;

2. The herein described method of making piston rings, which consists in slitting a ring blank circumferentially into a succession of slots with interspaced unslit portions, and thereafter grindin one edge of the ring, while the opposite e ge of the ring is supported against distortion or flexing.

3. The herein described method of making piston rings, which consists in slitting a ring blank circumferentially into a succession of arcuate slots with interspaced unslit portions, thereafter supporting the ring blank upon a flat surface and holding it in position on said surface by magnetism, and grinding the exposed edge of the ring while the ring is magnetically held in osition.

4. The herein described method of making piston rings, which consists in circumferentially slotting a ring blank to form therein a succession of arcuate slots with interspaced unslit portions, magnetically holding the thus sht ring for engagement with a fiat unyielding surface, and grinding the exposed edge of the ring while thus held firmly in positlon.

5. The herein described method of making piston rings, which consists in slotting a ring blank circumferentially to form in the blank a succession of spaced apart arouate slots, thereafter grinding one edge of the ring bla k while magnetically acting upon the blank to draw those portions of the blank contiguous to the slots in a direction away from the grinding tool.

6. The herein described method of makingpiston rings, which consists in forming in the circumference of a ring blank a succession of arcuate slots positioned with their contiguous ends spaced apart and the slots being of uniform width throughout, and thereafter surfacing one edge of the blank.

In testimony whereof I have signed foregoing specification.

HELEN W. HAMILTON.

the 

